Thermostat structure



April 20, 1943.

K. B. DAFFORN 2,317,033

THERMOSTAT STRUCTURE Filed April 14, 1941 a" INVENTOR. ZIEnneZ/pfiflaffbfm pear, and in which Patented Apr. 20, 1943 UNITED STATES PATENT OFFICE THEBMOSTA'I. s'ranc'runa Kenneth B. Morn, Dover, om, als ignor to Knapp-Monarch Company, St. Louis, corporation of Missouri My present invention relates to a thermostat structure for controlling electrically heated appliances, such as steam irons, sad irons, waille irons and the like.

One object of the invention is to provide a thermostat assembLv which may be secured to a surface from which heat is received for operating the thermostat and which includes an adjusting screw for the thermostat, the thermostat being designed to include an ofl" position,-

as well as various adjusted positions.

A further object is to provide a thermostat having a channel shaped casing with the various parts of the thermostat mounted therein and the casing including a mounting ear to be secured adjacent the heated surface of the appliance, with the bimetal element of the thermostat interposed between the mounting ear and such 'surface.

Still a further object is to provide a thermostat wherein spring arms carry circuit controlling contacts and are biased to disengage each other; 1

an adjusting screw being associated therewith to normally effect engagement except when the adjusting screw is rotated to a minimum or "off" position, a stop screw being engageable with one of the spring blades at such position to permit the same knob which is used for effecting adjustment to bealso used as a manual circuit opening control.

Other objects are to provide a thermostat assembly' wherein a plurality of stacked elements are secured as a unit with relation to the casin of the thermostat by a tubular rivet through which a mounting screw for one end of the thermostat extends, the stacked parts having coopcrating elements to prevent rotation thereof and consequent grounding of the spring arms of the thermostat relative to the casing.

Withthese and other objects in view, my invention with respect to its features which I believe to be novel and patentabie will be pointed out in the claims appended hereto. For a better detailed understanding ofthe invention, and further objects relative to details of economy of my invention, reference is made to the followin scription and to the accompanying drawing wherein such further objects will definitely ap- Figure 1 is a transverse vertical sectional view through an iron such as one of the steam generating type shown in the copending applies-- tion of Russell 1. Hu'flman, Serial No. 381.871,

therein and shown partially in section;

Figure'2 is an exploded perspective view of my thermostat structure;

Figure 3 is an enlarged sectional view on the line 2-2 of Figure 2, showing the bimetal element in heated position and the thermostat contacts separated as a result thereof;

Figure 4 is a similar sectional view on the line H of Figure 2, showing the adjusting screw for the thermostat rotated to its 011" position, and

Figure 5 is a sectional view on the line 5-5 of Figure 4.

On the accompanying drawing I have used the reference character S to indicate generally a sad iron, and S the solegplate thereof. My thermo-. stat is mounted within the shell of the sad iron and includes a casing C. The casing C is channel shaped, the web thereof being indicated at "land the flanges thereof at [2 and i. At one endof the casing C, the web it is bent down as at I! to form an end member and then bent out again as at It to form a mounting ear in a plane substantially parallel to the web I0. I

The web III has an upwardly depressed portion I! at its other end adapted to loosely receive a central huh I! of a first spacer indicated genorally at I. Second and third spacers 2 and 2 I are also provided and these spacers may be made of porcelain, or similar material. Each spacer has in its lower surface a depression IS. The depressions ll of the ijlrst and second spacers receive an' upwardly depressed portion 20 of a square washer 2|. The spacers I, 2 and 2 are stacked to surround a tubular rivet 22.

Also stacked on the tubular rivet 22 area pair of square washers of mica or the like, indicated at 22 and 2|. The stack also, includes an upper svrins arm 22, a lower spring arm 28, an upper terminal strip 21 and a lower terminal strip 28. The terminal strips 21 and 22 are adapted to beconnectedtoaterminaillandawirefl. respectively (see Figure 1). Current supply wir 2i and 22 are connected to the terminal 22 and a terminal 22. The wire 22 connected to the terminal strip 22 and another wire 24 connected (not shown) 01 the sad iron 8.

filed March 5, 1941. with my thermostat mounted' The sprint arms 22 and 22 extend from the tubular rivet 22 toward the opposite end of the casing C and carry contacts 2| and 26, respectively. In Figure 5, it will be noted that the spring arm 22 is-narrower than the distance between the flanges 12 and it of the casing Cso asnottobeshortcircuitedthereby. Toretain them in this position by preventing rotation ofthe'sprlng arms on the tubular rivet, the casing c has: a; pair of openings 31 to receive prongs 38 extending upwardly from the first spacer Similar prongs extend upwardly from the spacers 2 and 3 and enter sockets 28 therefor in the spacers and 2. The spring arms 25 and 25 each have notches indicated at 40 to receive the prongs 38 of the spacers 2 and 2. Thus the entire assembly of parts 2, 24, 2, 25, and is held against rotation relative to the web Id of the casing C. The hubs ll insulate the spring arms 25 and 26 from the tubular rivet 22 which is grounded, and the terminal strips 21 and 28 are provided witheyes large enough to surround the hubs l8 and thereby prevent grounding contact. The insulating washer 24 is also provided with. a pair of openings 4| to receive the prongs 38 of the spacer An adjusting screw 42 is provided for my thermostat which has an insulating tip 43 on its lower end and an adjusting knob 44 on its upper end. The knob 44 may be of insulating material secured as by screws 45 to a washer 45. The washer 46 has a stop lug 41 extending downwardly therefrom and adapted to engage a stop lug 4|.

in the minimum position of the lmob. The stop lug 48 is formed on a plate 49 supported on the shell of the sad iron, with a bore at 50 serving as a bearing for the adjusting screw 42.

The spring arm 25 is provided with an insulatlng button with which a bimetal element 52 is adapted to engage andwith which also a stop screw 53 is adapted to engage. The bimetal element 52 is mounted against the lower surface of the mounting ear It or between the surface of i the sole plate S and the mounting ear. A screw 54 extends through the ear and the bimetal G181 ment and is threaded into the sole plate to mount the end of the casing C having the ear It. To prevent rotation of the bimetal element on the screw 54 and consequent binding, the bimetal element is provided with a notch meeting with a lug 56 of the ear It. The bimetal element is also notched at 51 to clear the stop screw 53. The stop screw 53 is threaded through the web It of the casing C and has a spring 58 under its head toretain it in any adjusted positionf the bimetal'element 52 is cold the contact 35 is engaged with the contact 36 and the spring arms 25 and 28 assume a predetermined position, depending upon the setting of the knob 44. Consequently, when the bimetal element 52 is heated it will assume a position such as shown in this figure to engage the insulating button 5| and spring-the arm 25 downwardly for separating the circuit controlling contacts.- The position of the arm 26 as determined by the setting of the knob 44 will determine the degree of travel of the thermostat from cold to circuit opening position, and thus circuit opening may.

be eii'ected at various desired temperatures af- The adjusting screw 42 is threaded into a nut 59 which is mounted on the web Id of the casin O by passage through an opening 6|) thereof and a spinning operation performed at 5| on the lower I end of the nut to retain itin position. The end of the casing C opposite the screw 54 is retained on the sole plate 8' by a screw 52,- which extends through the tubular rivet 22.

Factory adjustment and practical operation.

In the operation of my thermostat, the parts shown explodedin Figure 2 are assembled toether, which includes the operation of stacking the elements shown in Figure 4 on the tubular rivet 22 and spinning the lower edge into the upwardly depressed portion 2B of the washer 2|.

After the operating range of the thermostat is determined, the knob 44 is secured in the proper position of rotation with respect to theadjusting screw 42 and then rotated to the stopped posi tion shown in Figure 1, with the lug 41 engaging the lug 40. This position is also shown in Figure 4. The stop screw 52 is then adjusted so that the contact" is Just S parated from the contact 35. Thereafter, the knob 44 may b ad. justed to various settings. and whenever it is returned to the stopped or "oil!" position the ther.

.mostat contacts will be separated.

fecting the bimetal element.

The parts of my thermostat, after being formed, may be readily and quickly assembled with relation to each other with a minimum of time and operations. The thermostat can be subsequently quickly adjusted for the desired temperature range and for the "off" position. The thermostat is so constructed as to intimately associate the temperature responsive element with the heated surface it is desirable to control. The metal casing C aids in heat transfer from the sole plate to the bimetal element by radiation from points entirely surrounding the bimetal element, as well as by conduction from the sole plate directly to the bimetal element.

I have illustrated and described my improvement in an embodiment which I have found very satisfactory. I have not attempted to illustrate or describe certain adaptations or modifications which I contemplate, or the various uses and adjustments possible, as it is believed that the foregoing disclosure will enable those skilled in the art to which this invention appertains to embody or adapt my improvements as may be desired.

Having thus described my invention, I now claim and desire to secure by Letters Patent:

1. A thermostat structure comprising achannel shaped casing having its web turned down at one end and spanning the distance between the flanges of the casing and terminating in a mounting ear located in a'plane substantially parallel to the web of the casing, a pair of spring arms, a contact carried by each spring arm. means adjacent the other end of said casing for mounting said spring arms so that they are biased to disengage each other comprising a tubular rivet, said spring arms having enlarged openings to receive said tubular rivet, afirst spacer between the web of said casing and one of said spring arms, a second spacer between said spring arms, a third spacer below the other spring arm, said spacers having central hubs receiving. the openings of said spring arms and face from which heat is received to operate the.

thermostat, an adjusting nut secured to the web of said casing, an adjusting screw threaded therein and enga in said one of said spring arms to eifect engagement of the contact thereof with the contact of said other spring arm, a bimetal element for moving said other spring am away from said one spring arm when the bimetal element is warped by heat, saidbimetal element being mounted against said ear, a screw through said ear and said bimetal element into said sur- ,iace from which heat is received, said other spring arm carrying an insulating button for eng ement by said bimetal element to separate the contact oi said other spring arm from the contact of said one spring arm at the operating point oi the thermostat, and a stop screw threadof spring arms, a contact carried by each spring arm, means adjacent the one end of said casing for mounting said spring arms therein so that they are biased to disengage each other comprising a tubular rivet, said spring arms having enlarged openings to receive said tubular rivet, a i'lrst spacer between said casing and one of said spring arms, a second spacer between said spring arms, a third spacer below the other spring arm, said spacers having central hubs receiving the -openings or said spring arms and prongs located spaced from said hubs, said spring arms and said casing having openings to receive said prongs for positioning said spring arms a inst rotation on said tubular rivet, an adjusting nut secured to said casing, an adjusting screw threaded therein and engaging said one or said spring arms'to eflect engagement of the contact thereof with the contact of said other spring arm, a bimetal element for moving said other spring arm away from said one spring arm when the bimetal element is warped by heat, said other spring arm carryin an insulating button ior engagement by said bimetal'element to separate the contact of said other spring arm from the contact of said one spring arm at the operating point or the thermostat when the bimetal element is warped by heat, and a stop screw carried by said casing and engaged by said insulating button to permit separation or the contact of said one v spring arm from the contact 01 said other sprin arm when said adjusting screw is adjusted to a minimum position, and a spring underthe head of said adjusting screw k to retain it in its adjusted position.

3. In a thermostat structure, a channel shaped casing having'a mounting ear at one end thereof, a pair or spring arms, a contact carried by ,rivet, a first spacer between the web 0! said casand one or said spring arms, a second spacer ..between said spring arms, a third spacer below 7 the other spring arm, said spacers having central hubs receiving the openings of said spring arm and prongs located spaced from said hubs, said spring arms and the web of said casing having openings to receivesaid prongs for positioning said spring arms against rotation on said tubular rivet, a screw through said tubular rivet entering a surface from which heat is received to operate said spring arms to eflect eng gement of the contact thereof with the contact of said other spring arm, a bimetal element 'tor moving said other spring arm away from said one spring arm when the bimeta'i element is warped by heat, said bimetal element being mounted against said ear, a screw through said ear and said bimetal element into said surface from which heat is received, said other spring arm carrying an insulating button for engagement by said bimetal element to separate the contact of said other spring arm from the contact or said one spring arm at the operating point o! the thermostat. and a stop screw threaded through said casing and enga in said insulating button to permit separation of the contact of said one spr arm from the contact of said other spring arm when said adjusting screw is adjusted. to a minimum position.

said bimetal element being notched to clear said stop screw.

4. A thermostat structure comprising a channel shaped casing having its web turned down at on end in a mounting ear, a pair of spring arms, a contact carried by each spring arm, means adjacent the other end of said casing ior mounting said spring arms so that they are biased to disengage each other comprising. a rivet, said spring arms having enlarged openings to receive said rivet, a first spacer between the web or said casing and one or said-spring arms, a second spacer between said spring arms, a third spacer, below the other spring arm, said spacers having central hubs receiving the openings of said spring arms, means for preventingv rotation of said spring arms on said rivet, an adjusting nut secured to the web of said casing, an adjusting screw threaded therein and eng in said one of said spring armsto eflect engagement oi! the contact thereof with the contact oi said other spring arm, a bimetal element for moving said other spring arm away from said one spring arm when the bimetal element is warped by heat, said bimetal element being mounted against said ear, said other spring arm carrying an insulating button for engagement by said bimetal element to separate the contact oi said other spring arm from the contact 01' said one spring arm at the operating point or the thermostat, and a stop screw engaging said insulating, button to separate the contact oi. said other spring arm from the contact of said one spring arm when said adjusting screw is adjusted to a minimum position.

5. A thermostat structure comprising a casing, a pair or spring arms, a contactcarried by each spring arm, means for mounting said spring arms so that they are biased to disengage each other comprising a single assembly element, said spring arms having enlarged openings to receive said assembly element, a first spacer between a wall oi! said casing and one of said spring arms, a second spacer between said spring arms, a third spacer below the other spring arm, said spacershaving central hubs receiving the openings of .said spring arms and having integral prongs located-spaced from said hubs, said spring arms I and said casing having openings to receive said 'prongs for positioning said spring arms against rotation on said single assembly element, an adjusting nut secured to said casing, an adjusting screw threaded therein and engaging said one 0! said spring arms to elect enga ement of the contact thereof with the contact or said other spring arm, and a bimetal element for moving said other spring arm away from said one spring arm when the bimetal element is warped by heat.

6. A thermostat structure comprising a channel shaped casing having its web turned down at by each spring arm, means adjacent the other end of said casing for mounting said spring arms so that they are biased to disengage each other comprising a tubular rivet, said spring arms having enlarged openings to receive said tubular rivet, a first spacer between'the web of said casing and one of said spring arms, a second spacer between said spring arms, a third spacer below the other spring arm, a screw through said tubuiar rivet entering a surface from which heat is received to operate the thermostat. an adjusting nut secured to the web 01 said casing,-an adjusting screw threaded therein and engasi-ns said one oi said spring arms to eiiect engagement oi the contact thereof withthe contact of said other spring arm, a bimetai element for moving said other spring arm away from said one spring arm when the bimetal element is warped by heat,

said bimetai element being mounted against said ear, a screw through said ear and said bimetal element into said surface from which heat is received, and a stop screw threaded through said web of said casing and enga ing said other spring arm to separate the contact thereof from the contact of said one spring arm when said adlusting screw is adjusted to a minimum position,

' said bimetal element being notched to clear said stop screw. I

KENNETH B. DAFFORN. 

